LHCb - Large Hadron Collider beauty experiment

Safety underground

The most hazardous part of the installation was threading the beryllium beam pipe through the detector, says Rolf Lindner. Beryllium is highly toxic, very expensive, and the pipe is very fragile - a screwdriver dropped from just a few metres above could easily have shattered it. Thankfully, however, there were no mishaps and the last piece of the pipe was slotted safely into place in summer 2007.

Another precarious task for the installation team was the construction of LHCb’s protective wall. Built out of concrete blocks, the wall will entirely seal off the detector when the experiment is underway, preventing people in the control rooms from being exposed to the radiation emitted as proton beams collide.

Several metres thick, the wall is constructed from 7.5 tonne concrete blocks, each of which had to be carefully lowered down the shaft using a crane and then moved across the cavern floor. Piling them up was extremely challenging, and not just because of their enormous weight; the floor of the cavern slopes slightly – a feature that had to be carefully compensated for. “The blocks have to fit very tightly together in order to protect against radiation,” explains Lindner. “You can't afford to leave even the smallest of gaps.”